DE102004033728A1 - Method for processing and bonding workpieces made of a metal or a metal alloy with a hydrated oxide and / or hydroxide layer - Google Patents

Abstract

A method for treating a bond area of a workpiece, and a method for adhesively bonding workpieces are disclosed. The method for treating a bond area of a workpiece includes cleaning the bond area, activating the bond area, coating at least a portion of the bond area with an adhesion promoter, and chemically transforming the adhesion promoter with an aftertreatment. The method for adhesively bonding workpieces includes cleaning a bond area of a first workpiece, activating the bond area, coating at least a portion of the bond area with an adhesion promoter, chemically transforming the adhesion promoter with an aftertreatment, applying an adhesive to the bond area, bringing the other workpiece into contact with the first workpiece, and curing the adhesive.

Description

The The invention relates to a method for processing an adhesive surface of a workpiece made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer and a method for bonding of two workpieces, where at least one workpiece made of a metal or a metal alloy with a hydrated oxide and / or hydroxide layer and the workpieces each have at least one an adhesive surface exhibit.

apart Of the precious metals, most metals and metal alloys a hydrated oxide and / or hydroxide layer. Metals or Metal alloys with a hydrated oxide and / or hydroxide layer are widely used in engineering, especially in industrial Production.

These Materials have hitherto been made by traditional bonding methods such as rivets, welding or screw connected. However, it turned out that these traditional connection methods associated with various disadvantages. There are, for example When the composite is loaded at the connection points, very high voltage peaks occur on. Furthermore, such traditional composites are often leaky and when connecting different materials arises many times Contact corrosion. After all In particular light metal materials, especially aluminum, are poorly suited for a weld together with other materials.

The Bonding of materials by gluing with adhesives is also a known connection method. Under the term adhesive understands one hereby a non-metallic material, the workpieces by surface adhesion (Adhesion) and internal strength (cohesion) connects with each other.

The Bonding brings compared to other bonding methods such as Riveting, welding and Screw numerous advantages. This gives a uniform distribution of stress over the entire adhesive surface, focusing on both static and dynamic strength positively affects. Furthermore, there is no violation of surface and microstructure. Additionally, adhesives can be used take a sealing function. Another advantage comes especially for lightweight construction, because of the use of adhesives a significant weight saving can be achieved. Not least can by adhesives also different materials interconnected become. Bonding typically takes place flat, in particular over the entire surface.

For a reliable and However, it is important for the strong bonding of materials adhesive surface pretreated so that the adhesive is a solid bond with the adhesive surface can go down. In particular, the metals or Metal alloys with a hydrated oxide and / or hydroxide layer the hydrated oxide and / or hydroxide layer formed in ambient air a problem. These naturally grown Layers are created in an irregular and not exactly defined process and have oxides, hydroxides and sometimes also Oxyhydroxides, often also present mixed.

by virtue of show the different structures of the products formed such natural grown surfaces Pores on which water is easily stored. At least in the top layer, hydration occurs. This surface layer has a bad connection and adhesion with the material surface and may result in unpredictable detachment or fractures within a load lead this oxide and / or hydroxide layer. Furthermore, the leads surface structure and hydration during bonding to a so-called "Weak Boundary Layer "and so on for premature failure of bonding these workpieces.

The adhesive surfaces have to also remain free of corrosion, so that the adhesive bond is not due to an occurring between the adhesive and the adhesive surface Reaction of the metal or metal alloy with moisture the environment is deteriorated and fails at continuous load.

One another problem of these surfaces, too if by additional Treatment method a defined oxide layer is applied, as for example with the anodizing (electrically oxidized aluminum) the case is that the oxide layer due to the low surface energy can only be badly wetted with an adhesive over the entire surface. The adhesive surfaces they are not sufficiently interconnected.

technical problem

Of the The present invention is therefore based on the technical problem the bonding of workpieces of metals or metal alloys with a hydrated oxide and / or hydroxide layer to improve.

description the invention

The previously indicated technical problem is according to a first teaching of the invention by a method for processing an adhesive surface of a workpiece of a metal or metal alloy with a hydrated oxide and / or hydroxide layer solved with the features of claim 1.

• – Reinigen der Klebefläche,
• – Aktivieren der Klebefläche,
• – Beschichten der Klebefläche zumindest teilweise mit einem Haftvermittler und
• – Nachbehandeln des Haftvermittlers.

The method according to the invention for processing an adhesive surface of a workpiece made of a metal or metal alloy with a hydrated oxide and / or hydroxide layer comprises the following method steps:

• - cleaning the adhesive surface,
• Activating the adhesive surface,
• - Coating the adhesive surface at least partially with a primer and
• - Post-treatment of the adhesion promoter.

At the Metal or metal alloy with hydrated oxide and / or hydroxide layer these are in particular the metals titanium, vanadium, Chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, magnesium, Aluminum and its alloys with each other or their alloys with other alloying constituents such as silicon or carbon. Among the alloys are in particular various steels and Aluminum alloys preferred. Particularly preferred are light metal materials such as aluminum, magnesium or titanium materials. A preferred one Material with a hydrated oxide and / or hydroxide layer is aluminum. After all can even materials such as silicon and silicon oxide (glass) have an oxide and / or hydroxide layer and therefore also fall in the scope of the present invention.

in the The invention will be described below with reference to the material aluminum. However, the invention is not limited to aluminum materials. Generally The invention relates to metals or metal alloys with a hydrated oxide and / or hydroxide layer.

Aluminum materials are versatile materials, for example, in the Vehicle production received an increasing share. Next For example, aluminum materials are also used in vehicle construction Construction of aircraft, for Parts of the building, especially for Facade parts or window frames, or for the manufacture of furniture or household appliances used. The reason for compared to the rising share other metals is mainly in the low weight.

Aluminum materials are manufactured in various ways adapted for later use. In vehicle construction, the aluminum material consists in particular of a Aluminum sheet, an aluminum extruded profile or an aluminum die cast alloy. A preferred alloy in vehicle construction consists of an aluminum-magnesium-silicon compound (AlMgSi). This is after processing by means of a coating process, in particular a cathodic dip coating after a pickling passivation painted and permanently opposite environmental influences protected.

In other areas of application is the aluminum material without a further painting exposed to environmental influences. In these Cases will the aluminum material targeted by an electrolytic oxidation with a protective Provided oxide layer. Such a material is also anodized (Electrically oxidized aluminum) known.

The adhesive surface is pretreated before the order of the primer, so cleaned and activated. As a result, the adhesive surface is in a largely defined Status. The aim here is that the surface of the adhesive surface predominantly, preferably almost completely no surface layer having undefined structure.

The Cleaning and activating the adhesive surface can either be done in one Step by means of a plasma treatment or an abrasive mechanical Treatment done. During the plasma treatment, the oxide layer remains the metal or metal alloy, in particular the aluminum oxide layer, exist while the abrasive technique largely removes them. Likewise, that can Clean and activate in two consecutive steps respectively.

Of the Adhesive is then applied to the cleaned and activated adhesive surface - with or without oxide layer - applied, then chemically in a post-treatment under the influence of energy is converted. When the glue is on the primer is applied, good adhesion properties and a result permanent adhesive bond.

By the pretreatment described above, ie cleaning and activating the adhesive surface of the workpiece Surface states are generated the conditions for offer good adhesion properties of the adhesive layers. For this reason it is advantageous to glue the pretreated workpieces either directly, subsequently or in one possible short time interval to a new deactivation the surface to avoid.

Clean

In order to improve the bondability of the metal or metal alloy surface with the hydrated oxide and / or hydroxide layer, it is advantageous to use the Surface state of the oxide and / or hydroxide layer and to change the degree of pollution. There are a number of mechanical, chemical and physical processes that are described below.

at the cleaning becomes the adhesive surface from superficial cleaned existing dirt. These soils are mainly hydrocarbons like fats and oils.

The Pretreatment of the adhesive surface can cause the after the production of the workpiece already resulting oxide and / or hydroxide layer on the surface either at least partially removed or in a permanent and firmly connected to the surface Condition is transferred.

The Energy supply for the pretreatment is preferably generated with a plasma source or plasma nozzle, in the means of a under application of a high-frequency high voltage in a nozzle tube between two electrodes by means of a non-thermal discharge a plasma jet is generated from a working gas. It stands the working gas preferably under atmospheric pressure, it is also called from an atmospheric Plasma. The method described is not on the application from atmospheric Limited to plasmas.

The plasma jet emerges from the nozzle opening, wherein one of the two electrodes is arranged in the region of the nozzle opening. The non-thermal plasma jet preferably has no electrical streamer outside the plasma nozzle at a suitably set flow rate, ie discharge channels of the electrical discharge, so that only the high-energy but low-tempered plasma jet is directed onto the adhesion promoter. The characterization of the plasma jet is also referred to as a high electron temperature and a low ion temperature. From the prior art of EP 0 761 415 A1 and the EP 1 335 641 A1 Such plasma sources are known per se.

In Preferably, the plasma jet with the help of an atmospheric Discharge generated in an oxygen-containing working gas. Thereby will the reactivity of the plasma jet increases. In preferably used as working gas air. Likewise, a Working gas used from a mixture of hydrogen and nitrogen be, a so-called forming gas.

The Non-thermal plasma discharge occurs in particular under application a high frequency high voltage, with a series of discharges is generated between two electrodes of the plasma nozzle and the working gas to one from the plasma nozzle exiting plasma is stimulated. Especially the high-frequency episode ensures discharges, that no thermal equilibrium arises in the discharge space. Thus, even in continuous operation, the imbalance between electron temperature and ion temperature are maintained.

The atmospheric Plasma treatment is particularly suitable for cleaning when It is about obtaining largely grease-free surfaces. The effectiveness of the plasma treatment depends of course the choice of process gas, performance, duration of treatment and of the plant concept and it can Adjustments can be made as required.

The method described above is less suitable for the removal of particle contaminants, such as chips or metal flakes and of inorganic impurities as salts or fingerprints, which can not be converted into gaseous products. Furthermore, the method is less suitable for very thick contamination layers, ie contamination by an oiling (corrosion protection oils and cutting / pressing oils) or by a dry lubricant, in the order of about 4 g / m ² suitable. Since the removal of the contamination layers can be iterative, even thicker layers can be removed, but there are economic problems. Therefore, in these cases of pollution, further pretreatment processes can be used either alternatively or in addition to plasma jet pretreatment.

Next the pretreatment of the adhesive surface by means an atmospheric Plasma jet it is also possible the adhesive surface mechanically, chemically and / or electrochemically or by means of a blasting process Pretreatment (laser, UV light, electron beam). Even if the thoroughness the pretreatment is not as extensive as in plasma pretreatment is, can these methods are also used.

• – Reinigen durch Waschen der Klebefläche mit Lösemitteln;
• – Mechanische Vorbehandlung durch Schleifen, Schmirgeln, Bürsten, Sandstrahlen oder CO₂-Strahlen;
• – Chemische Vorbehandlung durch Beizen mit sauren oder alkalischen Lösungen;
• – Thermische Verfahren durch Beflammung;
• – Elektrochemische Vorbehandlung durch Phosphatieren, Chromatieren, Entlackung oder Strippen;
• – Physikalische Vorbehandlung durch atmosphärisches Plasma, Corona-Entladung, UV-Behandlung, Laser, oder Normaldruck- oder Niederdruckplasma.

The purification within the method according to the invention is therefore not limited to the preferred application of the plasma treatment. Further examples of pretreatment are the following:

• - cleaning by washing the adhesive surface with solvents;
• - Mechanical pre-treatment by grinding, sanding, brushing, sandblasting or CO ₂ -radiation;
• - chemical pretreatment by pickling with acidic or alkaline solutions;
• - Thermal processes by flame treatment;
• - Electrochemical pretreatment by Phos phasing, chromating, stripping or stripping;
• - Physical pretreatment by atmospheric plasma, corona discharge, UV treatment, laser, or normal pressure or low pressure plasma.

When sand blasting and CO ₂ -radiation, a blasting agent of solid particles is directed at high speed on the surface to be treated. On the surface, the surface material, in particular the aluminum oxide layer, is deformed, compacted, compressed and / or removed by the impinging particles. The result is a rough aluminum material surface with a characteristic appearance. In contrast to most chemical surface treatment processes, blasting is comparatively environmentally friendly and, with the avoidance of dust pollution, also less risk in terms of occupational safety.

At the Low-pressure plasma procedures are the parts to be treated in one container introduced, the first is evacuated, and at an internal pressure of 10 to 500 Pa (fine vacuum) becomes some process gas, which preferably oxygen and noble gas is ionized. The improvement of the adhesive strength depends on Plasma gas and on the duration of treatment.

• – hoher Entfettungsgrad
• – keine Trocknung nötig
• – geeignet für alle Materialien
• – umweltfreundlich
• – geringe Betriebskosten
• – leicht steuerbarer Prozess
• – Änderung der Oberflächenenergie.
• – gute Klebfestigkeit.
• – die Klebungen sind alterungsbeständig.
• – anwendbar bei Lackierprozessen.
• – sehr lange Lagerfähigkeit.
• – schnelle Integrierbarkeit in Fertigungsabläufe.

It has been shown that plasma pretreatment and plasma cleaning have advantages over alternative methods. The most important advantages are:

• - high degree of degreasing
• - no drying necessary
• - suitable for all materials
• - environmentally friendly
• - low operating costs
• - easily controllable process
• - Change of surface energy.
• - good adhesion.
• - The bonds are resistant to aging.
• - applicable in painting processes.
• - very long shelf life.
• - fast integration into production processes.

Activate

According to the invention adhesive surface with an atmospheric Plasma jet activated, thus better wettability and a better responsiveness the adhesive surface for the Adhesive agent is achieved. It is of course preferred that the pretreatment and the activation of the surface in one step by means of an application of the plasma jet carried out becomes. In the listed alternative preparation methods is the step of activation optionally downstream of the plasma jet.

The Activating the further with an oxide and / or hydroxide layer Affected adhesive surface by means a plasma jet causes a modification of the oxide and / or Hydroxide layer on the surface of the workpiece. As a rule, the oxide and / or hydroxide layer lies before the activation, especially superficially, in a hydrated form. This is especially true when the oxide and / or hydroxide layer of the metal or metal alloy Uncontrolled occurred in ambient air.

During the Energy input through the plasma jet becomes the oxide and / or hydroxide layer dehydrated, causing a conversion to an oxide layer and optionally a modification of the crystal structure of the oxide he follows. In other words, it will be those in the oxide and / or Hydroxide layer existing water or OH groups removed. In particular, the use of plasma activation is suitable for this purpose.

The superficial, previously relatively soft hydrated oxide and / or hydroxide layer is thus consolidated and hardened.

There it is mainly at activation To get a high energy input, both oxidative and also non-oxidizing working gases used in the plasma generation become. Likewise, the activation of the metal or metal alloy surface, in particular the aluminum material surface, independently of it, whether during In the plasma treatment skip discharge channels (streamer) to the surface or not. The deciding factor is the transmission of a high power density the surface.

The so modified oxide surface is chemically active, so that the attachment of the adhesion promoter strong is simplified.

Surprisingly So it has been shown that when activated with a plasma jet the hydrated oxide and / or Hydroxide layer of the metal or metal alloy into one solidified form solidified and can be glued reliably, in particular without this a "weak boundary layer "arises.

Another type of surface activation is achieved in the above-described abrasive processes, in particular CO ₂ irradiation. In the abrasive process, the hydrated oxide and / or hydroxide layer is largely completely removed so that the metallic surface is exposed. This metallic surface is chemically active in itself, so that - preferably with a short time distance - the bonding agent is applied to the free surface of the material. During the aftertreatment, a direct bond is then produced between the primer and the metal or metal alloy surface. Depending on the material, an unhydrated, controlled oxide layer immediately forms immediately after exposure of the free metallic surface.

bonding agent

The The job of the adhesion agent is to have good adhesion between the metal or metal alloy surface and the adhesive to allow. Adhesion promoters therefore consist in most cases of dilute solutions of Adhesive base materials, which also for the subsequent bonding should be used.

The Bonding agents are usually applied to the workpieces by rolling, spraying or dipping and at temperatures below the later required curing temperature the adhesive is vented. While the ventilation time by typically a few minutes, the preferred one volatilizes solvent of the primer largely and under the influence of humidity may involve the crosslinking reaction of the primer substance and with the adhesive surface at least partially. This procedure ensures that that the adhesion promoter substance as homogeneous as possible on the Adhesive treated adhesive surface is distributed, so that after the following this was done after treatment a good bond to the metal or Metal alloy surface and to that later applied adhesive is ensured.

In Preferably, the adhesive surface is at least partially coated with a silane coupling agent.

Especially a coupling agent containing a composition is used or consists of at least one adhesion promoter substance, which is selected from the group comprising organosilicon compounds, organotitanium compounds and organo-zirconium compounds. These connections have become proved to be particularly advantageous. However, the invention is not limited to these connections.

The Adhesion promoter composition may also comprise mixtures of at least an organosilicon compound having at least one organotitanium compound and / or with at least one organozirconium compound. It may also be mixtures of at least one organotitanium compound containing at least one organozirconium compound. Prefers contains the primer composition mixtures of at least one Organosilicon compound with at least one organotitanium compound.

preferred Way, the adhesion promoter, a solvent, in particular volatile solvent on. Thus lets On the one hand, apply the primer well and evenly and on the other hand, the aftertreatment may already be shortly after application carried out by the bonding agent become.

aftercare

The Aftertreatment of the adhesion promoter takes place in a preferred manner by a plasma treatment and optionally an additional one Heat treatment.

at The plasma aftertreatment becomes the energy from the plasma jet transferred to the material of the bonding agent. Here is the Energy of the plasma gas, which has a high electron excitation, upon impact of the plasma on the surface of the primer at least partially transferred to the bonding agent.

The Post-treatment of the adhesion promoter is preferred with a plasma source or plasma nozzle carried out, in the means of a under application of a high-frequency high voltage in a nozzle tube between two electrodes by means of a non-thermal discharge from a preferably under atmospheric pressure working gas Plasma beam is generated. See the one already described above Operation of the plasma source.

by virtue of the high electron temperature is a high energy transfer on the bonding agent, without causing a strong heating up the material is coming. Therefore In turn, the low ion temperature is responsible. The chemical Energy of electron excitation can be directly involved in the reaction of the material be implemented by the adhesive agent. This will be a chemical Reaction of the primer with the adhesive surface, which is an exposed metallic surface or, preferably, has an oxide layer of a metal or a metal alloy, reached. This is a prerequisite for a strong bond of the later adhesive bond.

In Preferably, the adhesive surface is so with an atmospheric Aftertreated plasma jet, in particular a same plasma jet as used in the pretreatment of the adhesive surface. Therefore is it possible in principle the same plasma nozzle as well as to use the pretreatment as well as the aftertreatment.

Farther In addition to the Plasma-treatment another heat treatment be subjected to the curing reaction to complete. For the heat treatment the adhesion promoter is at least 5 minutes, preferably at least 10 min, at least 140 ° C, preferably at least 155 ° C, especially at least 170 ° C heated.

By the energy supply through the plasma jet and optionally through a heat supply is in the primer caused a chemical reaction and this chemically converted. Since no components of the organic radicals of the adhesion promoter with surface-analytical Methods, such as ESCA, demonstrated in measurable quantities can be It can be assumed that the adhesion promoter substance is used by the After treatment is largely decomposed and its semi-metal or Metal atoms, in particular Si and / or Ti and / or Zr, with the free metallic surface or the oxide surface of the metal or metal alloy. It will suppose that in this case insertion compounds, if appropriate Alloys, form.

By This chemical reaction during the aftertreatment makes the surface chemically modified. After completing the reaction is not a separate layer detectable. It therefore occurs in the context of the chemical reaction the post-treatment in contrast to the formation of a primer film with organic components, which by hydrolysis and crosslinking the adhesion promoter substances under the influence of moisture takes place, no deposition of a layer on the adhesive surface, but a chemical modification of the metallic or metal oxide surface of the material.

At least for the preferred material aluminum is the presumption that the activated alumina layer has a hexagonal honeycomb structure in which by the aftertreatment of the adhesion promoter the Silicon, titanium or zirconium atoms are stored. there is it then a nanoscale structure.

Finally, be mentioned, that after-treatment of the primer under special circumstances also by a sole heat treatment can be done.

glue

The Above indicated technical problem is inventively also by a method for bonding two workpieces solved, wherein at least one workpiece from a Metal or a metal alloy with a hydrated oxide and / or Hydroxidschicht consists and wherein the workpieces each at least one adhesive surface exhibit. The adhesive surface of the at least one workpiece made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer with a method according to the invention for processing an adhesive surface edited and for preparing the gluing.

Subsequently, will on at least one adhesive surface An adhesive is applied and the workpieces are filled with their adhesive surfaces Plant brought together. Finally, the adhesive is cured.

Consequently it is possible according to the invention, a stable and permanent bonding of two workpieces, of which a workpiece made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer consists. The second workpiece can of the same metal or metal alloy as the first workpiece made of a different metal or metal alloy with a hydrated oxide and / or hydroxide layer or from another material, like plastic or a natural one Fabric, persist. In any case, due to the pre-processing the adhesive surface good adhesion of the adhesive to the metal or metal alloy reached.

It gives a big one Selection of adhesives for the bonding of workpieces consisting of a metal or a metal alloy with a hydrated Oxide and / or hydroxide layer are suitable. It can one-component and multi-component adhesives are used.

component Adhesives have the big one The advantage that they do not have to be mixed and that errors, which occur due to incorrect mixing conditions or lack of mixing, can be excluded.

On the one hand come one-component adhesives used by physical Effects build up liability. These are, for example, solvents based adhesives containing non-reactive polymers as solutions or dispersions and solidify by drying, such as acrylic resin dispersion adhesives. Basically, these can Adhesives are used, but are only for bonding suitable in which only small forces must be transmitted and where they are applied over a large area become. For structural bonds, however, are not such adhesives suitable.

Also based on a physical strength structure adhesives provide the Non-reactive hot melt adhesives. In this case, a thermoplastic polymer is melted, hot applied to a Fügeteiloberfläche and immediately added. By cooling to room temperature, the polymer melt is solid and thus bonds the joining partners together. As a basis for such adhesives, a wide range of thermoplastic polymers is available, whereby the melting temperature, mechanics and adhesion of the hot melt adhesive can be varied within a wide range. A disadvantage of these non-reactive hotmelt adhesives is that the melting is a reversible process and consequently the risk of liquefaction of the adhesive at high temperatures, whereby the adhesive bond can be solved again.

Farther Reactive one-component adhesives are suitable for use. It These are either systems that are created by using a Energy source to be networked. The energy source can be particle or electromagnetic radiation, for example UV, visible Light, IR, microwave, electron or ion radiation, or Represent heat. For example, these are one-component acrylate, Epoxy resin, or polyurethane adhesives.

typically, In this case, such adhesives are used, which are a substance that react under the influence of radiation or heat or release a substance containing the reactive ingredients react the adhesive or initiate their polymerization or catalyze.

Examples for such Adhesives are thermosetting Epoxy or polyurethane adhesives with ingredients such as carboxylic acids, anhydrides, Dicyandiamide (dicy), amine adducts with Lewis acids, like boron compounds or acids, or amine-metal complexes.

Farther suitable for use are one-component adhesives which a Substance containing with ingredients of the air, in particular Humidity, react. This reaction already occurs at Room temperature. These are in particular one-component Polyurethane adhesives, which polyisocyanates, especially in the form Isocyanate-group-containing polyurethane prepolymers, which with react and cure the humidity.

When a special subclass of these are the reactive hot-melt adhesives to name, in particular the reactive polyurethane hotmelt adhesives, which either have a combination of isocyanate groups Prepolymer with thermoplastics or reactive thermoplastics include. Such hot melt adhesives are the non-reactive hot melt adhesives As a result of crosslinking by the isocyanate groups have no reversible melting behavior.

A another class of moisture-curing one-component adhesives contain as reactive compounds silane-containing polymers. Such adhesives are known to those skilled in the art as silicone adhesives, MS polymer adhesives or silane-terminated polyurethane adhesives.

Farther are as moisture-curing one-component adhesives, the cyanoacrylate adhesives, which, for example under the term "superglue" in public are known to mention.

The Two-component adhesives have the great advantage of having them the properties of the adhesive easy, for example by a use of another hardener component, the needs be adapted to the adhesive application, and that hereby very fast, extremely rigid or extremely elastic Gluing can be achieved.

When two-component adhesives are basically all known adhesives, which by a polyaddition or by a radical polymerization network. Here are the mutually reactive components stored separately and while or mixed immediately before use.

at the polyaddition, two types of compounds react with each other, which are stored separately from each other and an integral part of the respective components. These are commonly called resin and the other than hardeners designated.

The Classification of the adhesives is typically done via their Resin component.

epoxy adhesives contain compounds with oxirane groups, usually as glycidyl ethers present. The largest share containing epoxy resin adhesives Glycidyl ethers of bisphenols, in particular of bisphenol-A and / or Bisphenol-F, as a basic building block. As a hardener of two-component Epoxy resin adhesives are in particular polyamines and / or polymercaptans used. Preference is given to polyamines.

Two-component polyurethane adhesives contain polyisocyanates, in particular in the form of prepolymers having isocyanate groups. Hardeners used are polyamines and / or polyols and / or polymercaptans. The two-component adhesives are usually react significantly faster than two-part Epo xidharzklebstoffe.

adhesives, which crosslink by a radical polymerization are one another important class of suitable two-component adhesives. Here, a component by the admixing of an initiator, which releases free radicals, crosslinks. As compounds to be crosslinked, which form part of the first component, are usually Used compounds containing double bonds. Examples therefor are in particular styrenes, vinyl acetates, acrylonitrile, acrylates and Methacrylates used. Particularly suitable are the acids and Esters of acrylic acid and / or methacrylic acid. As a radical initiator, which is the second component or a component of which represent are usually Peroxides, in particular organic peroxides used. One of the most important Initiators is benzoyl peroxide.

These Adhesives have the big advantage fast networking and relatively low sensitivity across from Mixing errors.

For the present invention are preferably one-component thermosetting Epoxydharzklebstoffe, in particular with increased impact strength, as for example in EP 1 359 202 A1 are disclosed. These adhesives are preferably used as structural adhesives in vehicle construction.

Component polyurethane adhesives, such as are available under the product line Sikaflex ^® commercially available from Sika Switzerland AG are still preferred. In particular, these adhesives are used for bonding at room temperature.

As two-component adhesives, especially two-component polyurethane adhesives and (meth) acrylate adhesives are, as are available under the product lines SikaPower ^® respectively SikaFast ^® commercially by Sika Switzerland AG preferred.

These Adhesives are preferably used in the applications, where high cycle times and / or fast strength buildup is desired.

Especially for the Vehicle construction, it is advantageous that after curing of the Glue the glued workpieces with a cathodic dip coating to be painted. This allows components the bodywork are made after bonding the individual components uniform and almost no striking seams to be painted can.

One Advantage of the described method for bonding workpieces Metals or metal alloys with a hydrated oxide and / or Hydroxide layer is that by the pretreatment, the Applying the primer and bonding the workpieces one corrosion protected area arises.

One further advantage, in particular in the case of the application of plasma technology, is the low process time for pretreatment, for the application and aftertreatment of the adhesion promoter and for bonding. On the one hand, the low process time results from the fast Pre and post-treatment with the plasma jet and on the other by the low contact time of the bonding agent.

moreover results in a KTL compatibility of treated areas. Thus, the surfaces suitable to be used in further painting processes.

cathodic Dipcoating - KTL

at a further preferred embodiment of the present invention is the adhesive surface by means of a cathodic dip coating or dip coating coated. This ability is particularly useful in the practice of the present invention Vehicle construction of interest. Because the glued workpieces The described metals or metal alloys are usually also parts of the body, the before and / or after gluing one Painting process are subjected. This is mainly the aforementioned cathodic dip coating (KTL) used.

• – Entfettung (Tauchen bei +60°C)
• – Spülen (Tauchen in Betriebswasser)
• – Aktivierung (Tauchen)
• – Phosphatierung (Tauchen bei +45°C)
• – Spülen (Tauchen in Betriebswasser)
• – Passivierung (Tauchen)
• – Spülen (Tauchen in VE Wasser)

The workpieces are driven through the entire pre-treatment process as well as the electrocoating, which consist of the following work steps:
First comes the pretreatment.

• - degreasing (diving at + 60 ° C)
• - rinsing (immersion in process water)
• - Activation (Diving)
• Phosphating (immersion at + 45 ° C)
• - rinsing (immersion in process water)
• - passivation (diving)
• - rinsing (immersion in deionized water)

After this process, the actual painting process, the electrocoating takes place. Electrocoating is a coating process that uses electrochemical processes to deposit anticorrosive paint. An electro-diving system applies a DC voltage to a workpiece, which is immersed in a paint bath with oppositely charged paint particles. The paint particles are thus attracted to the workpiece, deposited on it and form there a uniform film over the entire surface. Every column and corner is covered, even hidden surfaces, until the given attraction is stopped and the KTL - coating is completed. After this has been done, the workpiece passes through rinsing zones that work with fully desalted (VE) water. After leaving the rinsing zones, the coated parts enter the baking oven. There, the paint film crosslinks and hardens to achieve maximum resistance of the coatings.

Therefore it is desirable that with the adhesive coated adhesive surface also with the conventional one Procedure can be painted. It does not just matter that the glued surface, So the adhesive itself is dip-coatable, but that too have the adhesion promoter adhesive surfaces having this property. Because the area occupied by the adhesive usually does not cover Completely the area of the primer, but it pass over the adhesive sections in addition, areas on whose outer surface also is occupied after bonding with the primer. These too Areas should be as possible be dip-coatable, because then the KTL coating to the adhesive layer comes close and thus protected against corrosion. In the area of the splice takes over the adhesive is the task of passive corrosion protection, taking a good one for that and as possible all-over Adhesion of the adhesive with the surface is essential. Under passive corrosion protection is understood that the adhesive has a barrier effect against the leading to corrosion Substances, but not actively prevented corrosion of the surface. Ideally, the adhesive property of the adhesive is as good as that of the lacquer layer deposited by KTL, or preferably better.

During the Dip coating or dip coating are applied at least two layers, wherein the layer thickness difference less than 25% based on the thinnest layer is. This will be a more even and stable construction achieved.

The Above indicated technical problem is inventively also by a workpiece solved, the one adhesive surface wherein at least the adhesive surface of a metal or a Metal alloy with a hydrated oxide and / or hydroxide layer consists. According to the invention adhesive surface glued by a method according to any one of claims 15 to 23.

Especially is the workpiece a vehicle body, in particular an automobile body. Prefers it is as well that the workpiece is a part of a vehicle, especially an automobile.

Specific Description of exemplary embodiments

Hereinafter, an embodiment of a plasma source, which is suitable for carrying out the method, and chemical compositions of adhesion promoters, which can be used in the invention, explained in more detail. For this purpose, reference is made to the accompanying drawings. In the drawing shows the only one 1 a plasma nozzle for generating a plasma jet in a schematic representation.

plasma source

In the 1 shown plasma nozzle 10 has a nozzle tube 12 made of metal, which tapers to an outlet opening 14 rejuvenated. At the outlet opening 14 opposite end has the nozzle tube 12 an inlet 16 for a working gas, for example for compressed air. An intermediate wall 18 of the nozzle tube 12 has a ring of inclined in the circumferential direction employed holes 20 and thus forms a swirl device for the working gas. The downstream, conically tapered portion of the nozzle tube is therefore of the working gas in the form of a vortex 22 flows through, the core of which runs on the longitudinal axis of the nozzle tube.

At the bottom of the partition 18 is an electrode in the middle 24 arranged coaxially protrudes into the tapered portion of the nozzle tube. The electrode 24 is formed by a rotationally symmetric, rounded at the tip pin, for example made of copper, by an insulator 26 electrically opposite the partition 18 and the remaining parts of the nozzle tube is isolated. About an insulated shaft 28 gets to the electrode 24 a high frequency alternating voltage applied by a high frequency transformer 30 is produced. The voltage is variably adjustable and is for example 500 V or more, preferably 2-5 kV, in particular more than 5 kV. The frequency is for example in the order of 1 to 30 kHz, preferably in the range of 20 kHz, and is preferably also adjustable. The shaft 28 is with the high frequency transformer 30 via a flexible high voltage cable 32 connected. The inlet 16 is connected via a hose, not shown, with a compressed air source with variable throughput, preferably with the high frequency generator 30 is combined to a supply unit. The plasma nozzle 10 Can be easily moved by hand or with the help of a robot arm. The nozzle tube 12 and the partition 18 are grounded.

The applied voltage causes a high-frequency discharge in the form of an arc charge 34 between the electrode 24 and the nozzle tube 12 generated. Due to the swirling flow of the working gas, however, this arc is in the vortex core on the axis of the nozzle tube 12 channeled so that it is only in the area of the outlet opening 14 to the wall of the nozzle tube 12 branched. The working gas that is in the area of the vortex core and thus in the immediate vicinity of the arc 34 rotated at high flow rate, comes into intimate contact with the arc and is thereby partially transferred to the plasma state, so that a beam 36 a relatively cool atmospheric plasma, such as in the shape of a candle flame, from the outlet opening 14 the plasma nozzle 10 exit.

The illustrated embodiment shows an example of a number of different embodiments from plasma sources. Therefore, the described embodiment not limiting for the protection area to understand the object.

bonding agent

Of the The adhesion promoter used in the described process contains a Composition or consists of at least one adhesion promoter substance, the selected is from the group comprising organosilicon compounds, organotitanium compounds and organo-zirconium compounds. These connections have become proved to be particularly advantageous. However, the invention is not limited to these connections.

In principle, all organosilicon compounds known to the person skilled in the art and suitable as organosilicon compounds which are used as adhesion promoters are suitable. The organosilicon compound preferably carries at least one group which hydrolyzes under the influence of water and leads to the formation of a silanol group. Such an organosilicon compound preferably carries at least one, in particular at least two, alkoxy group which is or are bonded directly to a silicon atom via an oxygen-silicon bond. Furthermore, the organosilicon compound carries at least one substituent which is bonded via a silicon-carbon bond to the silicon atom, and which optionally has a functional group which is selected from the group comprising oxirane, hydroxy, (meth) acryloxy, amino , Mercapto and vinyl groups. Such amino, mercapto or oxirane group-containing organosilicon compounds are also referred to as "aminosilanes", "mercaptosilanes" or "epoxysilanes". In particular, the organosilicon compound is a compound of the formula (I)

The substituent R ^{1 in} this case represents a linear or branched, optionally cyclic, alkylene group having 1 to 20 C atoms, optionally with aromatic moieties, and optionally with one or more heteroatoms, in particular nitrogen atoms. The substituent R ² is an alkyl group having 1 to 5 C atoms, in particular methyl or ethyl.

Furthermore, the substituent R ^{3 is} an alkyl group having 1 to 8 C atoms, in particular methyl and the substituent X is an H, or a functional group which is selected from the group comprising oxirane, OH, (meth) acryloxy, amine , SH and vinyl.

Finally it stands a for one the values 0.1 or 2. Preferably, a = 0.

Preferred substituents R ¹ are methylene, propylene, methylpropylene, butylene or dimethylbutylene. Preferably, R ^{1 is} a propylene group.

suitable Organosilicon compounds are readily available commercially and are particularly preferably selected from the group comprising 3-methacryloxypropyltrialkoxysilanes, 3-aminopropyltrimethoxysilane, bis [3- (trimethoxysilyl) -propyl] -amine, tris [3- (trimethoxysilyl) -propyl] -amine, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyl-dimethoxymethylsilane, 3-amino-2-methylpropyltrimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyl-dimethoxymethylsilane, 4-amino-3-methylbutyl-trimethoxysilane, 4-amino-3,3-dimethylbutyl-trimethoxysilane, 4-amino-3,3-dimethylbutyl-dimethoxymethylsilane, 2-aminoethyltrimethoxysilane, 2-aminoethyldimethoxymethylsilane, Aminomethyltrimethoxysilane, aminomethyldimethoxymethylsilane, Aminomethylmethoxydimethylsilane, N- (2-aminoethyl) -3-aminopropyldimethoxymethylsilane, 7-amino-4-oxaheptyldimethoxymethylsilan, (3- (trimethoxysilyl) propyl] urea, 1,3,5-tris [3- (trimethoxysilyl) propyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione-urea (= isocyanurate of 3-isocyanatopropyltrimethoxysilanes), 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, Vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, Octyltrimethoxysilane, dodecyltrimethoxysilane and hexadecyltrimethoxysilane and adducts of epoxysilanes with mercaptosilanes or with aminosilanes.

Preferred adducts of epoxysilanes with aminosilanes or mercaptosilanes are those which are used as reaction product D in the EP 1 382 625 A1 are described.

When Organosilicon compounds most preferred are aminosilanes, in particular those with primary Amino groups, preferably 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane and mixtures thereof.

Basically as organotitanium compound all organotitanium compounds known to the person skilled in the art, which are used as adhesion promoters suitable. Prefers wears the Organo-titanium compound at least one group which under the influence hydrolyzed by water and leads to the formation of a Ti-OH group. Prefers wears a such organo-titanium compound at least one functional group wearing, which are selected is selected from the group comprising alkoxy group, sulfonate group, carboxylate group Acetylacetonate, or mixtures thereof, and which carries over Oxygen-titanium bond is bonded directly to a titanium atom.

Particularly suitable alkoxy groups are so-called neoalkoxy substituents, in particular the following formula

Particularly suitable sulfonic acids are aromatic sulfonic acids whose aromatic groups have been substituted by an alkyl group. Preferred sulfonic acids are radicals of the following formula

When Carboxylate groups are especially carboxylates of fatty acids especially proved suitable. Preferred carboxylates are decanoate.

In all the above formula shows the dashed bond here Connection to the titanium atom.

Organo-titanium compounds are commercially available, for example from Kenrich Petrochemicals or DuPont. Examples of suitable organo-titanium compounds are, for example, Ken-React ^® KR TTS, KR 7, KR 9S, KR 12 KR 265, KR 33DS, KR 385, KR 39DS, KR44, KR 134S, KR 138S, KR 158FS, KR212, KR 2385, KR 262ES, KR 138D, KR 158D, KR238T, KR 238M, KR238A, KR238J, KR262A, LICA 38J, KR 55, LICA1, LICA 09, LICA 12, LICA 38, LICA 44, LICA 97, LICA 99, KR OPPR , KROPP2 Kenrich Petrochemicals or Tyzor ^® ET, TPT, NPT, BTM AA, AA-75, AA-95, AA-105, TE, ETAM from DuPont. Preferably, Ken-React ^® KR 7, KR 9S, KR 12 KR 265, KR 38S, KR44, LICA 09, LICA 44, NZ 44, as well as Tyzor ^® ET, TPT, NPT, BTM, AA, AA-75, AA apply -95, AA-105, TE, ETAM by DuPont.

Basically as organozirconium compound all organozirconium compounds known to the person skilled in the art, which are used as adhesion promoters suitable. Prefers wears the Organo-zirconium compound at least one group which under hydrolyzed by the influence of water and to form a Zr-OH Group leads. Preferably carries such an organozirconium compound is at least one functional one Group wears, which are selected is selected from the group comprising alkoxy group, sulfonate group, carboxylate group, Carries phosphate or mixtures thereof, and which via an oxygen-zirconium bond is bonded directly to a zirconium atom.

Particularly suitable alkoxy groups are isopropoxy and so-called neoalkoxy substituents, in particular the following formula

Particularly suitable sulfonic acids are aromatic sulfonic acids whose aromatic groups have been substituted by an alkyl group. Preferred sulfonic acids are radicals of the following formula

When Carboxylate groups are especially carboxylates of fatty acids especially proved suitable. Preferred carboxylates are stearate.

In all the above formula the gestri In this case, the bond was smiling at the connection to the zirconium atom.

Organozirconium compounds are commercially available, for example NZ 38J, NZ TPPJ, KZ OPPR, KZ TPP, NZ 01, NZ 09, NZ 12, NZ38, NZ 44, NZ 97 from Kenrich Petrochemicals. Preferred is Ken-React® ^NZ44 .

The Adhesion promoter composition may comprise mixtures of at least one Organosilicon compound with at least one organotitanium compound and / or with at least one organozirconium compound. It may also be mixtures of at least one organotitanium compound containing at least one organozirconium compound. Prefers contains the primer composition mixtures of at least one Organosilicon compound with at least one organotitanium compound.

Especially Preference is given to mixtures of several organosilicon compounds or mixtures from an organosilicon compound with an organo-titanium compound. As mixtures of organo-silicon compounds have particularly good mixtures of adhesion promoter substances of the formulas (I), where at least one of these substituents H carries as substituent X. and at least one of these substances is a functional group, which are selected is selected from the group comprising oxirane, (meth) acryloxy, amine, SH and Vinyl, as a substituent X carries. These mixtures are preferably at least one Alkyl trialkoxysilane with an aminoalkyl trialkoxysilane and / or mercaptoalkyl trialkoxysilane.

Prefers are volatile Solvents like Water, alcohols, in particular ethanol, isopropanol, butanol, aldehydes or ketones, in particular acetone, methyl ethyl ketone, hydrocarbons, especially hexane, heptane, cyclohexane, xylene, toluene, white spirit as well as their mixtures. Particularly preferred are ethanol, Methanol, isopropanol or hexane, and mixtures thereof. The salary on solvent is usually between 0 and 99% by weight, in particular between 50 and 99% by weight, preferably between 90 and 99 wt .-%, based on the weight of Adhesive composition. Furthermore, the adhesion promoter composition if required usual Additives, in particular leveling agents, defoamers, surfactants, biocides, anti-settling agents, Stabilizers, inhibitors, pigments, dyes or odorants, contain.

Farther it may be advantageous, especially when using a paint binder, when the primer composition contains a filler. preferred fillers are soot, fumed silicas and chalks, their surfaces has been modified if necessary.

The Preparation of the adhesion promoter composition is carried out by a person skilled in the art in a known manner, typically with exclusion of moisture. The adhesion promoter composition will after the preparation stored in suitable containers, which the Contact with moisture during prevent storage. Preference containers are plastics, glass and metals. Particularly preferred are aluminum containers, especially aluminum bottles with tight lids.

The adhesion promoter composition is applied by spraying, in particular as a film, or by application by means of a cloth, felt or brush. Upon the application of a textile fabric, such as a paper towel (Tela or Kleenex ^®) is typically soaked with the adhesive composition and applied to the surface to be treated.

Claims (26)

Method for processing an adhesive surface of a Workpiece where at least the adhesive surface of a metal or metal alloy with a hydrated one Oxide and / or hydroxide layer is, - When the adhesive surface cleaned becomes, - at the adhesive surface is activated, - at the adhesive surface at least partially coated with a primer and - in which the adhesion promoter chemically converted by a post-treatment becomes. The method of claim 1, wherein the adhesive surface with an atmospheric one Plasma jet is cleaned. Method according to Claim 1 or 2, in which the adhesive surface is mechanical, chemically and / or electrochemically or by means of a blasting process, in particular by means of laser, UV light or electron beam, cleaned becomes. The method of claim 3, wherein the hydrated Oxide and / or hydroxide layer is at least partially detached from the workpiece. Method according to one of claims 1 to 3, wherein the adhesive surface with an atmospheric plasma jet is activated. The method of claim 5, wherein the hydrated Oxide and / or hydroxide layer is dehydrated and solidified. The method of claim 6, wherein the metal or metal alloy is hydrated Oxide and / or hydroxide layer is a light metal material, in particular aluminum or an aluminum alloy. Method according to one of claims 1 to 7, wherein a bonding agent is used, which contains a composition or from at least one Adhesive agent consists, which is selected from the group comprising Organosilicon compounds, organo-titanium compounds and organozirconium compounds. Method according to one of claims 1 to 8, wherein the adhesion promoter a solvent, especially a volatile solvent having. Method according to one of claims 1 to 9, wherein the adhesion promoter having a paint binder. Method according to one of claims 1 to 10, wherein the adhesion promoter a filler having. Method according to one of claims 1 to 11, wherein the adhesion promoter by means of an atmospheric Plasma jet is treated. The method of claim 12, wherein the adhesion promoter by means of a heat treatment is further treated. The method of claim 13, wherein the adhesion promoter at least 5 minutes, preferably at least 10 minutes, at least 140 ° C, preferably at least 155 ° C, especially at least 170 ° C heat treated becomes. Method for bonding two workpieces, wherein at least one workpiece made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer and wherein the workpieces each at least one adhesive surface exhibit, - at the adhesive surface of the at least one workpiece made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer with a method according to one of claims 1 to 14 is processed, - at on at least one adhesive surface an adhesive is applied, - in which the workpieces with their adhesive surfaces be brought into contact with each other and - In which the adhesive is cured. Method according to claim 15, in which both workpieces are made a metal or metal alloy with a hydrated one Oxide and / or hydroxide layer exist. The method of claim 15 or 16, wherein the metal or the metal alloy with a hydrated oxide and / or Hydroxide layer a light metal material, in particular aluminum or an aluminum alloy. Method according to one of claims 15 to 17, in which as Adhesive a one-component adhesive is used. The method of claim 18, wherein as an adhesive an epoxy resin and / or a polyurethane is used. Method according to one of claims 15 to 17, in which as Adhesive a two-component adhesive, especially epoxy adhesive and / or a polyurethane adhesive is used. The method of claim 20, wherein a hardener component, preferably consisting of polyamines, polycarboxylic acids, isocyanates or hydroxy-containing resins. A method according to any one of claims 15 to 22, wherein curing of the adhesive, the bonded workpieces with a cathodic dip coating to be painted. The method of claim 22, wherein in the dip coating at least two layers are applied and in which the layer thickness difference less than 25% based on the thinnest layer. Workpiece, With an adhesive surface, where at least the adhesive surface made of a metal or a metal alloy with a hydrated one Oxide and / or hydroxide layer is, characterized, that the adhesive surface is bonded by a method according to any one of claims 15 to 23. workpiece according to claim 24, wherein the workpiece is a vehicle body, in particular a Car body is. workpiece according to claim 24, wherein the workpiece is a part of a vehicle, especially an automobile.